The present invention relates to an information processing system to execute online processing and batch processing, and in particular, to a method of recovering data stored on a storage media such as a storage, for example, a disk destroyed by a failure or the like of online processing and/or batch processing.
In online processing and batch processing executed in an information processing system of a bank, a securities company, or the like, when the processing is abnormally terminated by a bug of a program, a failure of a storage, or the like, integrity of data may be lost depending on cases. Important data may be destroyed or erased by a mistake made by a human working in the information processing system.
There have been known several techniques which restore the information processing system in such a failed state and which solve conflict of data integrity to restart the processing interrupted or to execute again the processing interrupted. One of such recovery technique uses xe2x80x9cbackup and restorationxe2x80x9d.
In the recovery of xe2x80x9cbackup and restorationxe2x80x9d, for example, when the recovery is applied to a database system, a backup of data is periodically stored on a recording media such as a magnetic tape. At occurrence of a failure in the system, the backup on the magnetic tape is restored in the storage to recover the data of the storage up to an appropriate point using a log file. The database data is resultantly recovered to an appropriate state and the database processing can be restarted.
In batch processing system, data is stored as backup data on a magnetic tape before batch processing is started. When the processing is thereafter abnormally terminated, the backup data is read from the magnetic tape to restore data of the storage to a state before the start of batch processing. The batch processing is then re-executed beginning at its start point.
When data is restored in the recovery of xe2x80x9cbackup and restorationxe2x80x9d of the prior art, data in the areas on the magnetic tape not updated from when the backup data is stored (data in the areas whose data matches that stored in the storage) is also read from the magnetic tape and is written in the storage. This data transfer is actually unnecessary and elongates the period of time required for the restoration (reference is to be made to FIG. 17A).
In a case in which areas A, B, and C are specified as a backup and restoration unit in the storage, when each area thereof is individually accessed and hence only area A is required to be recovered, the restoration is carried out for areas A to C. This also elongates the restoration time. During the data restoration, processing which uses data in areas A to C must be interrupted. This adversely influences efficiency of the overall processing (reference is to be made to FIG. 17B).
It is therefore an object of the present invention to provide a data recovery method, which solves the problems of the prior art, to increase the data restoring speed using the backup data to thereby minimize the period of time required to restore the system from to a normal state.
To achieve the object above in accordance with the present invention, in an information processing system including a central processor and a storage subsystem including a storage media such as a disk to execute a data transfer in response to a request from the central processor, before data on the disk is updated by a sequence of processing, the information processor issues to the storage subsystem a saving request to save a copy of data stored on a storage media such as a disk used in the sequence of processing. In response to the saving request, the storage subsystem saves a copy of data on the storage media. When the contents of the storage media is updated in a sequence of processing by the central processor, the storage subsystem stores differential information including an area updated. When it is necessary to restore the contents of the storage media to a state of a particular point of time, the storage subsystem restores, in response to a data restoring request from the central processor, the saved data on the storage media according to the differential information stored.
According to one aspect of the present invention, in an information processing system including a central processor and a storage subsystem including a storage media such as a disk to execute a data transfer in response to a request from the central processor, the storage subsystem restores, in response to a restoring request from the central processor, backup data of data, which is kept on a first storage media storing data of a logic volume to be accessed by the central processor, on a second storage media. The storage subsystem establishes, in response to a swap request from the central processor, a relationship between the logic volume and the second storage media. Thereafter, in response to an access request to the logic volume from the central processor, the storage subsystem accesses data in the second storage media.